4-92 Mr. Fox's Experiments on Subterranean Electricity 



When the former, which call No. 1, was placed in the cir- 

 cuit, the needle was deflected so as to become stationary 

 at 14° to 15° from zero; and it revolved rapidly round the 

 circle when the circuit was broken and restored a few times, the 

 direction of the electricity being from the south vein to the 

 northern one. The other galvanometer (No. 2) suffered a 

 permanent deflection of about 40° when in the circuit. The 

 interposition of a plate of platinum or zinc at either of the ore- 

 points, or of a point, instead of a considerable surface of me- 

 tal, did not affect the direction or force of the currents; they 

 were, moreover, constant in both these respects during more 

 than eight months that the two veins were connected by the 

 wires, and a part of this time the mine was filled with water 

 in consequence of an accident to the machinery. Ore-points 

 in the two veins situated within two or three feet of the others 

 respectively, were at one time connected by a second pair of 

 copper wires of the same lengths as the first ; both sets of par- 

 allel wires being kept apart, and insulated from the sides of the 

 levels or galleries by poles stretched across the latter at short 

 intervals. 



When galvanometer No. 2 was placed in the second cir- 

 cuit, No. 1 remaining in the other, the needle of the latter re- 

 ceded at least 2°, standing at 12°, instead of 14° or 15°; and 

 the former stood at 5° or 6° less than it did when only one 

 circuit was established. On breaking either of the circuits, 

 the deflection of the needle in the other circuit was increased 

 to its original amount; and when both pairs of wires were con- 

 nected with only one of the instruments, the effect was almost 

 precisely the same as that produced by one pair alone, — not 

 greater certainly. 



A copper and zinc pair of plates of about 6 inches surface, 

 separated by a piece of cotton cloth moistened with water, was 

 placed in the circuit, and when the currents from this source 

 and the veins coincided in direction, the needle of galvano- 

 meter No. 1 stood at eibout 10°, that is, at less than it did 

 when acted upon by the subterranean electricity alone, and 

 when the deflection caused by the latter was afterwards op- 

 posed by the action of the plates, the needle went back to 

 zero, and even sometimes passed a little beyond it in the op- 

 posite direction. These anomalies may perhaps be referred 

 to the low conducting power of the moistened cotton, which, 

 small as its thickness was, very probably interrupted the trans- 

 mission of the electricity more than the 14 or 18 fathoms of 

 strata or "Country." 



On taking the voltaic elements from the circuit and con- 

 necting them with the galvanometer, so as to form a separate 



